Endoscopic resection method

ABSTRACT

Embodiments of the invention are directed to a method of excising tissue including injecting fluid into the submucosa to raise targeted tissue. A first electrode is positioned below the targeted tissue within the injected fluid and a second electrode is positioned adjacent a surface of the raised targeted tissue opposite the first electrode. Electrical current is applied between the first and second electrodes and the targeted tissue is excised with the second electrode.

FIELD OF THE INVENTION

Embodiments of this invention relate to methods for removing tissue froma patient. More particularly, at least certain embodiments of theinvention relate to methods for endoscopic mucosal resection includinginjecting fluid into tissue, positioning wire snares at a treatmentsite, and applying current between the snares in order to cut and removetissue.

BACKGROUND OF THE INVENTION

Endoscopic methods are commonly used for diagnosis and/or treatment ofinternal anatomical lumens within a patient's body, such as, forexample, the gastrointestinal tract. For example, there are severalmethods, known as endoscopic mucosal resection, for treating bothmalignant and non-malignant tumors within a patient's mucosa (the mucoustissue lining various internal anatomical lumens consisting ofepithelium, lamina, propria, and, in the gastrointestinal tract, a layerof smooth muscle). Endoscopic mucosal resection may include snaring andthen excising sessile adenomas (i.e., tumors attached to a bodilysurface) in an anatomical lumen. If the adenoma is flat against thelumen wall, thus making it difficult to snare and excise, one of severalmethods may be used to raise the flat adenoma so that it may be snaredand excised. One method includes using forceps to raise the flatadenoma. Another method includes using a vacuum to raise the flatadenoma. A further method, called hydrodissection includes injectingfluid into the submucosa so as to create a pocket or opening below thetissue to raise the flat adenoma above the underlying tissue.

Once the adenoma is excised, bleeding into the body lumen may resultfrom the underlying portion of the tissue from which the adenoma wasremoved. These, and other medical procedures (e.g., staining, marking,and identifying tissue), may involve making an incision in body tissueand controlling any consequent bleeding. When performing theseprocedures, it may be desirable to minimize both tissue trauma duringincision and the time required to stop internal bleeding. In addition,it is desirable to cleanly cut and retrieve a uniform tissue sample ofsufficient size particularly where a pathology study of the sample isnecessary. Furthermore, it is desirable for the resection to leave cleanmargins at the treatment site in order to minimize any furtherdisruption of the surrounding anatomy.

Minimally invasive or least invasive surgical techniques, such aslaparoscopic, endoscopic, or arthoroscopic techniques, are sometimesused because body tissue is usually traumatized less by those techniquesthan by more invasive conventional techniques. Electrosurgicalmethodologies, sometimes used in conjunction with the minimally or leastinvasive techniques, allow the making of an incision and the stopping orstemming of bleeding with less attendant tissue trauma and greatercontrol than do conventional modalities. While useful in stemming theflow of blood resulting from tissue resection, electrosurgical methodscan often cause unnecessary burning or trauma beyond the desiredtreatment site and into the surrounding anatomical lumen wall during aresection procedure.

The aforementioned methods, while effective, have certain drawbacks. Asphysicians sometimes use different devices to perform differentfunctions, for example, use one catheter to make an incision and anotherto perform hemostasis or irrigation, the exchange of catheters toprovide different functions extends the time to complete therapy,increases the risk to the patient, and also increases patientdiscomfort. Consequently, physicians have to weigh the time, complexity,and benefits of interchanging single or dual purpose catheters to changetreatment modalities against whatever disadvantage may result by workingwith a single catheter.

Thus, it is desirable to present a method for endoscopic mucosalresection that overcomes the disadvantages of the prior art to, asexamples, retrieve a uniform tissue sample adequate for pathology study,maintain clean tissue margins, reduce trauma to the surrounding anatomy,and control the depth of burning attendant to electrosurgery.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to methods forremoving tissue from a patient. More particularly, at least certainembodiments of the invention relate to methods for endoscopic mucosalresection that obviate one or more of the limitations and disadvantagesof prior resection methods.

One embodiment of the invention is directed to a method of excisingtissue in a body, comprising injecting fluid into the submucosa to raisetargeted tissue and positioning a first electrode below the targetedtissue within the injected fluid. A second electrode is positionedadjacent a surface of the raised targeted tissue opposite the firstelectrode. Current is then applied between the first and secondelectrodes and the targeted tissue is excised with the second electrode.

In various embodiments, the method may include one or more of thefollowing additional features: inserting an endoscope into an anatomicallumen of the body, positioning the endoscope proximate the targetedtissue, inserting an injection needle through a working channel of theendoscope to the targeted tissue, and injecting the fluid through theinjection needle; wherein the injected fluid raises the targeted tissuethrough the creation of a fluid pocket within the tissue; wherein thefirst and second electrodes are not connected; wherein the first andsecond electrodes are independently moveable; wherein the firstelectrode is an electrically conductive snare loop; wherein the snareloop is inserted within the injected fluid through an injection needle;wherein the snare loop is movable between a retracted state within alumen of the needle and an expanded state positioned distally beyond thelumen of the needle; wherein the second electrode is an electricallyconductive snare loop; wherein the first and second electrodes arepositioned at an excision site through a placement catheter having firstand second lumens housing the first and second electrodes; wherein thefirst and second electrodes are electrically conductive snare loops,each snare loop being movable between a retracted state and an expandedstate; wherein current is applied between the first and secondelectrodes, such that one of the first electrode and the secondelectrode is an active electrode and the other of the first electrodeand the second electrode is a return electrode in a bipolar circuit;wherein the snare loop is movable within an insulating lumen between aretracted state and an expanded state, the method further comprisingselecting the amount of conductive snare loop to expose in order tocontrol a current applied to the targeted tissue; wherein the snare loopis movable within a lumen of a medical device between a retracted stateand an expanded state such that the snare loop excises the raisedtargeted tissue upon retraction of the snare loop into the lumen;wherein applying current coagulates tissue; wherein the injected fluidis a non-ionic fluid; wherein attracting magnets are disposed on eachelectrode such that the electrodes align when positioned.

Another embodiment of the invention is directed to a method of excisingtissue in a body, comprising injecting an electrically conducting fluidbelow targeted tissue and positioning an electrode adjacent a surface ofthe targeted tissue opposite the electrically conducting fluid. Aconductor is positioned below the targeted tissue to contact theelectrically conducting fluid. Current is applied between theelectrically conducting fluid and the electrode and the targeted tissueis excised with the electrode.

In various embodiments, the method may include one or more of thefollowing additional features: wherein the fluid is a conductive gel;wherein the electrode is an electrically conductive snare loop; whereinthe snare loop is housed within a flexible sheath and is movable betweena retracted state within a lumen of a sheath and an expanded statepositioned distally beyond the lumen of the sheath; inserting anendoscope into an anatomical lumen of the body; positioning theendoscope proximate the targeted tissue; and inserting an injectionneedle through a working channel of the endoscope to the targetingtissue; and injecting the electrically conducting fluid through theinjection needle; wherein an injection needle for injecting the fluid ispositioned proximate the targeted tissue through a first lumen of aplacement catheter and the electrode is positioned through a secondlumen of the placement catheter; wherein current is applied between theelectrically conducting fluid and the electrode, such that one of thefluid and the electrode is an active electrode and the other of thefluid and the electrode acts as a return electrode in a bipolar circuit;wherein the snare loop is movable within an insulating lumen between aretracted state and an expanded state, the method further comprisingselecting the amount of conductive snare loop to expose in order tocontrol the current applied to the targeted tissue; wherein the snareloop is movable within a housing lumen of a medical device between aretracted state and an expanded state such that the snare loop excisesthe targeted tissue upon retraction of the snare loop into the lumen;wherein applying current coagulates tissue; wherein the injectedconductive fluid raises the targeted tissue through the creation of afluid pocket within the tissue; wherein the conductive fluid is injectedinto the submucosa to raise the target tissue.

Another embodiment of the invention is directed to a method of excisingtissue in a body, comprising inserting a first snare loop below targetedtissue and positioning a second snare loop adjacent a surface of thetargeted tissue opposite the first snare loop. Current is appliedbetween the first and second snare loops and tissue is excised with thesecond snare loop.

In various embodiments, the method may include one or more of thefollowing additional features: wherein the second snare loop is notconnected to the first snare loop; wherein the first and second snareloops are independently moveable; injecting fluid into the submucosabelow the targeted tissue to raise the targeted tissue and positioning afirst electrode below the targeted tissue within the injected fluid;positioning the endoscope proximate the targeted tissue; inserting aninjection needle through a working channel of the endoscope to thetargeted tissue; and injecting the fluid through the injection needle;wherein each of the first and second snare loops are movable withinseparate lumens of a medical device between retracted and expandedstates such that the snare loops may excise the raised targeted tissueupon retraction of a snare loop into a lumen; wherein current is appliedbetween the first and second snare loops, such that one of the first andthe second snare loops is an active electrode and the other of the firstand second snare loops is a return electrode in a bipolar circuit.

Additional objects and advantages of the invention will be set forth inpart in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the invention. Theobjects and advantages of the invention will be realized and attained bymeans of the elements and combinations particularly pointed out in theappended claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates the placement of an injection needle through anendoscope into an anatomical lumen with an adenoma, according to anembodiment of the invention.

FIG. 1B illustrates an injection needle piercing the tissue below anadenoma within an anatomical lumen, according to an embodiment of theinvention.

FIG. 1C illustrates an injection needle infusing fluid into the tissuebelow an adenoma within an anatomical lumen, according to an embodimentof the invention.

FIG. 2 illustrates a placement catheter positioning another injectionneedle within the anatomical lumen of a patient, according to anembodiment of the invention.

FIG. 3 illustrates positioning a snare loop within a fluid pocket formedbelow an adenoma within an anatomical lumen, according to an embodimentof the invention.

FIG. 4 illustrates the placement of first and second snare loops withinan anatomical lumen, according to an embodiment of the invention.

FIG. 5 illustrates a placement catheter within an anatomical lumen of apatient after the completion of a resection procedure, according to anembodiment of the invention.

FIG. 6 illustrates an alternative resection procedure, according to anembodiment of the invention.

FIG. 7 illustrates another alternative resection procedure, according toan embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present exemplaryembodiments of the invention illustrated in the accompanying drawings.Wherever possible, the same reference numbers will be used throughoutthe drawings to refer to the same or like parts.

FIG. 1A illustrates an endoscope 10 positioned within a patient'sanatomical lumen 30 for the treatment of a sessile adenoma 40. Aninjection needle 12 is positioned within the anatomical lumen 30 througha working channel of the endoscope 10. The injection needle 12 includesa shaft 14, a piercing tip 16 having a bevel 18 and an opening 20 at itsdistal end (i.e. the end further from the operator during use). Duringendoscopic treatment procedures, injection needles are often used, forexample, to introduce irrigation fluids at a treatment site, injectvaso-constrictor fluid into a vessel to slow hemorrhaging, or inject asclerosing agent to control bleeding varices by hardening the targetedtissue.

Referring to FIG. 1B, the endoscope 10 housing the injection needle 12,is positioned at the site of the sessile adenoma 40. The needle 12 ispositioned such that the bevel 18 of the piercing tip 16 is insertedinto tissue at the base of the adenoma 40. FIG. 1C illustrates ahydrodissection procedure within the anatomical lumen 30. Duringhydrodissection, temporary bulking of tissue occurs by the injection offluid at a tissue treatment site to separate certain tissue layers. Inthe present method, hydrodissection of tissue is performed in order tofacilitate the snaring and excision of an adenoma by injecting fluidinto the submucosa so as to create a pocket or opening below the tissueto raise the flat adenoma above the underlying tissue. As seen in FIGS.1C and 2, after the bevel 18 pierces the adenoma 40, injection fluid 22is infused at the base of the adenoma 40 along the anatomical lumen 30.

During hydrodissection, a bolus of sterile solution is injected into thetissue, resulting in an opening or fluid pocket 24. The volume of fluidinjected into the tissue in the hydrodissection procedure is too largeto be rapidly absorbed such that the tissue must separate to accommodatethe fluid. In the present invention, the injection needle 12 preferablycreates a fluid pocket 24 by injection of a fluid 22 into the desiredtreatment site to lift the resection target. Examples of specific fluidsinclude, but are not limited to, hydrooxypropyl methyl cellulose,hyaluronic acid, or saline (which may also include epinephrine). Becausethe injected fluid 22 is not immediately absorbed, the fluid pocket 24creates a raised adenoma 72.

FIG. 2 shows a placement catheter 50 including a first lumen 52 and asecond lumen 54. As illustrated, the first lumen 52 houses an injectionneedle 62 including a shaft 64, a piercing tip 66 having a bevel 68 andan opening 70 at its distal end. The catheter 50 is positioned in orderto allow the injection needle 62 to reach the raised adenoma 72.Referring to FIG. 3, the injection needle 62 is positioned so as topierce the raised adenoma placing the opening 70 of the needle 62 withinthe fluid pocket 24 previously created by injection needle 12 of FIGS.1A-1C.

In an alternative embodiment, the hydrodissection could be performedusing positioning catheter 50 and infusing the injection fluid 22through needle 62. Such an arrangement obviates the need for theseparate injection needle 12.

Referring again to FIG. 3, the injection needle 62 houses anelectrically conductive snare loop 74 within the internal lumen of theneedle shaft 64. The snare loop 74 is capable of being moved between aretracted state within the lumen of the needle 64 and an expanded statepositioned distally beyond the opening 70 of the needle. The snare loop74 may be formed of any material capable of conducting electricity andsuitable for resilient movement between expanded and retracted states.Exemplary materials include, but are not limited to, stainless steel andnickel titanium alloys commonly referred to as nitinol.

As illustrated in FIG. 3, once the opening 70 of the injection needle 62is positioned within the fluid pocket 24, the electrically conductivesnare loop 74 is extended outside the needle opening 70 and placedwithin the fluid pocket 24. The electrically conductive snare loop 74may be connected at its proximal end (i.e. the end closer to theoperator during use) to a source of high frequency current (not shown)capable of energizing the snare loop 74 to act as a electrosurgicaltreatment electrode upon the activation of the current source. Snareloop 74 also may be connected to any suitable actuator (such as a wire)that extends through needle 62 to a proximal end of the device. Theactuator may connect to any suitable handle at the proximal end that isused to extend and retract snare loop 74 relative to needle 62. Theactuator also may conduct electric current to loop 74 and connect at theproximal end to a source of electric current.

Referring to FIG. 4, the second lumen 54 of the placement catheter 50houses a second electrically conductive snare loop 76. The second snareloop 76 is capable of being moved between a retracted state within thesecond lumen 54 and an expanded state positioned distally beyondcatheter 50. FIG. 4 illustrates the second electrically conductive snareloop 76 in the expanded state distally beyond the second lumen 54 ofcatheter 50 and positioned to surround an upper outside surface of theraised adenoma 72. Just as described above with regard to the firstsnare loop, the second snare loop 76 may be formed of any materialcapable of conducting electricity and suitable for resilient movementbetween expanded and retracted states. Exemplary materials include, butare not limited to, stainless steel and nickel titanium alloys commonlyreferred to as nitinol. In addition, the electrically conductive snareloop 76 may also be connected at its proximal end to a source of highfrequency current (not shown) capable of energizing the second snareloop 76 to act as a electrosurgical treatment electrode upon theactivation of the current source. And, snare loop 76 may be connected toan actuator wire extending through lumen 54 to a proximal handle. Thefirst and second snare loops 74, 76 are independently movable relativeto each other for proper placement at the desired treatment site.

In the resection method according to an embodiment of the currentinvention, high frequency current is applied, through the use of asource of high frequency power source (not shown), to flow between thefirst electrically conductive snare 74 and the second electricallyconductive snare 76. The current can be applied such that the first andsecond snares act as first and second bipolar electrodes, with one snareacting as the active electrode and the other acting as the returnelectrode to complete a bipolar electrically circuit. Upon theapplication of current between the first and second electricallyconductive snares 74 and 76, the raised adenoma 72 can be excised uponthe tightening, or closing, of the second snare loop 76 throughretraction proximally within the second lumen 54 of the catheter 50. Thecurrent flowing between the first and second snares provides sufficientenergy to assist in cutting through the target tissue while acting tocoagulate and/or cauterize the underlying tissue site along theanatomical lumen 30.

Alternatively, only one of the electrically conductive snares 74, 76 maybe connected to a source of current. In such a configuration, the oneelectrically conductive snare would act as a monopolar electrode toassist in cutting through the target tissue while acting to coagulateand/or cauterize the underlying tissue site along the anatomical lumen30. The current flowing from the monopolar snare electrode would returnto the current source and complete the electric circuit through, forexample, a patient ground return electrode often positioned externallyon the patient's back.

The catheter 50 is preferably formed of a non-conducting polymermaterial. Similarly, injection needle 62 may be formed with a coating ofan insulating polymer material incapable of conducting electricity.Accordingly, the flow of current between the first and secondelectrically conductive snares 74,76 can be altered by an operatorcontrolling the amount of exposed area of the electrically conductivesnare 74,76 beyond the insulating materials of needle 62 and catheter50. Because both electrically conductive snares 74 and 76 can beselectively movable between retracted and expanded states, the operatorcan precisely control the amount of exposed conductive material servingto pass current between the snares 74,76.

Depending on such factors as the type of tissue targeted for resection,the impedance of the injection fluid 22, and the desired effect ontreatment tissue, the operator may change the direction of current flowbetween the first and second electrically conductive snares 74,76. Forexample, the operator may choose, depending on the treatment procedure,to modify the flow of current such that in one operation, the firstelectrically conductive snare 74 acts as the active electrode in thebipolar circuit, and later in another operation the second electricallyconductive snare 76 acts as the active electrode in the bipolar circuit.Such versatility allows the operator to more precisely affect thecurrent flow through the targeted tissue and to control the resultingeffect at the treatment site.

Referring to FIG. 5, after the mucosal resection procedure, the firstand second electrically conductive snares 74 and 76 are moved to theirrespective retracted states. In addition, the injection needle 62 isalso withdrawn proximally into the first lumen 52 of the placementcatheter 50 and withdrawn from the anatomical lumen 30 outside of thepatient. The resected adenoma 78 can then be captured with a separateretrieval instrument if pathology study of the tissue sample isnecessary.

FIG. 6 depicts an alternative method according to an embodiment of thepresent invention. Placement catheter 50 is illustrated as positioned ata desired treatment site within an anatomical lumen 30. FIG. 6 differsfrom the prior embodiment in that the injection fluid infused to createthe fluid pocket 24 is an electrically conductive fluid or gel 86. Inthis embodiment, an injection needle similar to the injection needle 12of FIG. 1 can positioned to extend within the fluid pocket 24 and act asa first electrode in the application of high frequency current duringthe resection procedure. Alternatively, a simple flexible conductor 84,such as, for example, a conducting wire capable of being extended intothe tissue pocket 24, may be used to connect the conductive fluid or gel86 to a source of high frequency current. Conductor 84 may also serve asan additional resection tool during a treatment procedure.

In addition, the second lumen 54 of the placement catheter 50 mayinclude a flexible sheath 80 that houses the electrically conductivesnare loop 76. The flexible sheath 80 may facilitate more accuratepositioning of the snare loop 76 at the treatment site. In theembodiment of FIG. 6, current is passed between the conductive gel 86and the snare loop 76 to provide sufficient energy to assist in cuttingthrough the target tissue while acting to coagulate and/or cauterize theunderlying tissue site along the anatomical lumen 30. The use ofconductive fluid or gel is advantageous in that is can serve the dualpurposes administering hydrodissection and acting as an electrode duringthe application of high frequency current.

FIG. 7 depicts an additional feature according to an embodiment of thepresent invention. FIG. 7 illustrates an endoscopic mucosal resectionprocedure for excising a raised adenoma 72, include a placement catheter50 and first and second electrically conductive snare loops 74,76. Inorder to facilitate proper alignment between electrodes, the snare loops74 and 76, which act as the first and second electrodes in a bipolarcircuit, include an alignment mechanism. In one embodiment, magnets82A-82B and 84A-84B are provided along the first and second snare loops74,76. FIG. 7 depicts the first conductive snare loop 74 positionedwithin the fluid pocket 24. The pair of magnets 82A and 82B aremagnetically attracted toward each other in order to align the proximalends of the first and second snares 74 and 76 in order to more preciselyposition the electrodes.

In addition, another pair of magnets 84A-84B are provided along thedistal portion of the first and second snares 74 and 76. The pair ofmagnets 84A and 84B are magnetically attracted toward each other inorder to align the distal ends of the first and second snares 74 and 76in order to more precisely position the electrodes during a resectionprocedure. While the embodiment shows a pair of magnets associated witheach snare loop, more or less magnets may be used. In addition, themagnets may be positioned at other locations along the snare loop.

Alternative alignment mechanisms can be used in place of the magnetembodiments described above. For example, alignment could be achievedwith markers on the proximal end of the device indicating how much ofeach snare surface has been deployed. Furthermore, radiopaque markerscould replace the magnets described above. In such an embodimentvisualization techniques such as, x-ray, MRI, fluoroscopy, andendoscopic visualization could be performed to achieve proper alignmentof the snares. Additionally, various electronic transducers could bedisposed in place of, or in addition to, the magnets described above.For example, piezoelectric transducers could be disposed along thesnares to control movement and bending of the snare to aid in alignmentand positioning of the snare loops. Another arrangement includes the useof photo-detector and photo-emitter transducers disposed along thecorresponding portions of the snare loops in order to provide feedbackto a user regarding the relative positioning and alignment of the snareloop structure.

It is to be understood that any feature described with reference to aparticular figure or embodiment may be repeated in and utilized in anyof the other embodiments or figures disclosed in this application. Forexample, it is intended that any embodiment may include the use ofaligning magnets and the first and second snares.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

1. A method of excising tissue in a body, comprising: injecting fluidinto the submucosa to raise targeted tissue; positioning a firstelectrode below the targeted tissue within the injected fluid through aninjection needle having a distal portion incapable of conductingelectricity; positioning a second electrode adjacent a surface of theraised targeted tissue opposite the first electrode; applying currentbetween the first and second electrodes; excising the targeted tissuewith the second electrode.
 2. The method of claim 1, wherein theinjecting comprises: inserting an endoscope into an anatomical lumen ofthe body; positioning the endoscope proximate the targeted tissue;inserting the injection needle through a working channel of theendoscope to the targeted tissue; and injecting the fluid through theinjection needle.
 3. The method of claim 1, wherein the injected fluidraises the targeted tissue through the creation of a fluid pocket withinthe tissue.
 4. The method of claim 1, wherein the first and secondelectrodes are not connected.
 5. The method of claim 1, wherein thefirst and second electrodes are independently moveable.
 6. The method ofclaim 1, wherein the first electrode is an electrically conductive snareloop.
 7. The method of claim 6, wherein the snare loop is movablebetween a retracted state within a lumen of the needle and an expandedstate positioned distally beyond the lumen of the needle.
 8. The methodof claim 1, wherein the second electrode is an electrically conductivesnare loop.
 9. The method of claim 1, wherein the first and secondelectrodes are positioned at an excision site through a placementcatheter having first and second lumens housing the first and secondelectrodes.
 10. The method of claim 9, wherein the first and secondelectrodes are electrically conductive snare loops, each snare loopbeing movable between a retracted state and an expanded state.
 11. Themethod of claim 1, wherein current is applied between the first andsecond electrodes, such that one of the first electrode and the secondelectrode is an active electrode and the other of the first electrodeand the second electrode is a return electrode in a bipolar circuit. 12.The method of claim 6, wherein the snare loop is movable within aninsulating lumen of the injection needle between a retracted state andan expanded state, the method further comprising selecting the amount ofconductive snare loop to expose in order to control a current applied tothe targeted tissue.
 13. The method of claim 8, wherein the snare loopis movable within an insulating lumen of the injection needle between aretracted state and an expanded state, the method further comprisingselecting the amount of conductive snare loop to expose in order tocontrol a current applied to the targeted tissue.
 14. The method ofclaim 8, wherein the snare loop is movable within a lumen of a medicaldevice between a retracted state and an expanded state such that thesnare loop excises the raised targeted tissue upon retraction of thesnare loop into the lumen.
 15. The method of claim 1, wherein applyingcurrent coagulates tissue.
 16. The method of claim 1, wherein theinjected fluid is a non-ionic fluid.
 17. The method of claim 1, whereinattracting magnets are disposed on each electrode such that theelectrodes align when positioned.
 18. The method of claim 1, furthercomprising adjusting an amount of current by enclosing at least aportion of the first electrode with the injection needle.
 19. The methodof claim 18, wherein the first and second electrodes are electricallyconductive snare loops, each snare loop being movable between aretracted state and an expanded state.
 20. The method of claim 18,wherein the first electrode is movable within an insulating lumen of theinjection needle between a retracted state and an expanded state.
 21. Amethod of excising tissue in a body, comprising: injecting fluid intothe submucosa with an injection needle to raise targeted tissue, theinjection needle having a distal portion incapable of conductingelectricity; inserting a first snare loop below the targeted tissuethrough the injection needle; positioning a second snare loop adjacent asurface of the targeted tissue opposite the first snare loop; applying acurrent between the first and second snare loops; insulating the currentby retracting at least a portion of the first snare loop into theinjection needle; and excising the tissue with the second snare loop.22. The method of claim 21, wherein the second snare loop is notconnected to the first snare loop.
 23. The method of claim 21, whereinthe first and second snare loops are independently moveable.
 24. Themethod of claim 21, further comprising: inserting an endoscope into ananatomical lumen of the body; positioning the endoscope proximate thetargeted tissue; and inserting the injection needle through a workingchannel of the endoscope to the targeted tissue; wherein injecting fluidincludes injecting fluid through the injection needle.
 25. The method ofclaim 21, wherein each of the first and second snare loops are movablewithin separate lumens of a medical device between a retracted state andan expanded state such that at least one of the first and second snareloops may excise the raised targeted tissue upon retraction of the atleast one of the first and second snare loops into a lumen.
 26. Themethod of claim 21, wherein current is applied between the first andsecond snare loops, such that one of the first and the second snareloops is an active electrode and the other of the first and second snareloops is a return electrode in a bipolar circuit.
 27. A method ofexcising tissue in a body, comprising: inserting an injection needleinto an anatomical space of the body, a distal portion of the injectionneedle including a first electrical insulator; piercing adjacent atarget tissue with a tip of the injection needle; injecting fluidthrough a lumen of the injection needle to form a fluid pocket beneaththe target tissue; inserting a first electrode through the lumen of theinjection needle and into the fluid pocket; inserting a second electrodethrough a lumen of a medical device having a distal portion including asecond electrical insulator; positioning a distal tip of the secondelectrode outside of the distal portion of the medical device adjacentthe target tissue and opposite the first electrode; applying a currentbetween the first and second electrodes; and controlling the current byretracting at least one of the first and second electrodes into thelumen of the injection needle and the lumen of the medical devicerespectively.
 28. The method of claim 27, wherein controlling thecurrent includes retracting the first electrode into the lumen of theinjection needle.
 29. The method of claim 27, wherein controlling thecurrent includes retracting the second electrode into the lumen of themedical device.
 30. The method of claim 27, wherein controlling thecurrent includes retracting the first electrode into the lumen of theinjection needle and retracting the second electrode into the lumen ofthe medical device.
 31. The method of claim 27, wherein the firstelectrode is an electrically conductive snare loop.
 32. The method ofclaim 27, wherein the second electrode is an electrically conductivesnare loop.
 33. The method of claim 27, further comprising inserting thefirst electrode into the fluid pocket when the tip of the injectionneedle is in the fluid pocket.
 34. The method of claim 27, wherein thedistal portion of the injection needle is incapable of conductingelectricity.
 35. The method of claim 27, wherein current is appliedbetween the first and second electrodes, such that one of the firstelectrode and the second electrode is an active electrode and the otherof the first electrode and the second electrode is a return electrode ina bipolar circuit.
 36. The method of claim 32, further comprisingexcising the targeted tissue by proximally retracting the second snareloop.
 37. The method of claim 27, further comprising insulating thecurrent by retracting at least a portion of the first electrode into thelumen of the injection needle.